Early weaning stress induces chronic functional diarrhea, intestinal barrier defects, and increased mast cell activity in a porcine model of early life adversity

Supplementation of protease to low amino acid diets containing superdose level of phytase for wean-to-finish pigs: effects on performance, postweaning intestinal health and carcass characteristics

This experiment investigated the effects of protease supplementation to low amino acid (AA) diets containing phytase on pig growth performance, postweaning intestinal health and carcass characteristics. A total of 936 weaned pigs (21 d of age, initial BW 5.87 ± 0.31 kg) were used in a 2 × 2 factorial design comparing the main effects of AA supply [standard feeding program: balanced for all nutrients with adjustment of Ca and P due to inclusion of phytase (2,500 FTU/kg in Phase 1 to 4; 500 FTU/kg in Phase 5 to 9) vs. low AA feeding program: 15% lower standardized ileal digestible lysine with relative reduction of all other essential AA] and protease level (0 vs. 0.0125%). Pens were assigned to dietary treatment according to a randomized complete block design with 26 pigs per pen and nine replicates per dietary treatment. Feed and water were provided on an ad libitum basis for all phases throughout the wean-to-finish period. Feed intake and body weight were determined every 2 wk during nursery period and monthly in the grow-finish period. Intestinal health in the first 17 d was assessed based on lactulose:mannitol ratio (L:M), serum IgA, and pen diarrhea assessment. Overall, pigs fed standard wean-to-finish diets had greater (P < 0.05) ADG and G:F than pigs fed low AA diets. Pig growth performance was not different throughout the wean-to-finish period with or without protease supplementation and with no interaction between AA supply and protease supplementation. There were no differences among dietary treatments for carcass characteristics. No difference was observed for urinary L:M and serum IgA; however, the L:M ratio was approximately 32% lower in pigs fed low AA diets + protease compared with pigs fed standard and low AA diets at d 5 and d 17 postweaning. Pigs fed protease supplemented diets had lower incidence of diarrhea (χ² < 0.05) compared with pigs fed diets without protease. Results of the experiment indicate that dietary protease supplementation benefits intestinal health of nursery pigs.

Effects of stress-related peptides on chloride secretion in the mouse proximal colon

BACKGROUND

Stress increases intestinal secretion and exacerbates symptoms of irritable bowel syndrome (IBS). Peripherally derived corticotropin-releasing factor (CRF) is known to mediate stress-induced intestinal secretion, presumably by activation of CRF₁ receptors in the gut. The present study aimed to ascertain the role of CRF₂ activation in intestinal secretion by three other members of CRF peptide family, urocortin (UCN) 1-3, in wild type (WT) and CRF₂ knockout (Crhr2^-/- ) mice.

METHODS

Mucosal/submucosal preparations from proximal colon of WT and Crhr2^-/- mice of both sexes were mounted in Ussing chambers for measurement of short-circuit current (I_sc ) as an indicator of ion secretion.

KEY RESULTS

Male mice demonstrated a significantly higher baseline I_sc than female in both WT and Crhr2^-/- genotypes. CRF and UCN1-3 (1 μM) caused greater increases in colonic I_sc (ΔI_sc ) in male than female. Colonic I_sc response to the selective CRF₁ agonist, stressin1, was similar in both sexes. In male mice, the selective CRF₂ agonists (UCN2 and UCN3) caused significantly greater ΔI_sc than CRF and stressin1. UCN2- and UCN3-evoked ΔI_SC was significantly reduced in preparations pretreated with the selective CRF₂ antagonist antisauvagine-30 and in Crhr2^-/- mice. The prosecretory effects of urocortins were due to increases in Cl^- secretion and involved enteric neurons and mast cells.

CONCLUSIONS AND INFERENCE

The findings revealed sex differences in baseline colonic secretion and responses to stress-related peptides. CRF₂ receptors play a more prominent role in colonic secretion in male mice. The greater baseline secretion and responses to UCNs may contribute to the higher prevalence of diarrhea-predominant IBS in males.

Influences of Selenium-Enriched Yeast on Growth Performance, Immune Function, and Antioxidant Capacity in Weaned Pigs Exposure to Oxidative Stress

This study elucidated the function role of dietary selenium-enriched yeast (SeY) supplementation on growth performance, immune function, and antioxidant capacity in weaned pigs exposure to oxidative stress. Thirty-two similarity weight pigs were randomly divided into four treatments: (1) nonchallenged control, (2) control+SeY, (3) control+diquat, and (4) control+SeY+diquat. The period of experiment was 21 days; on day 16, pigs were injected with diquat or sterile saline. Results revealed that oxidative stress was notably detrimental to the growth performance of piglets, but SeY supplementation ameliorated this phenomenon, which might be regarding the increasing of body antioxidant capacity and immune functions. In details, SeY supplementation improved the digestibility of crude protein (CP), ash, and gross energy (GE). Moreover, the serum concentrations of proinflammatory cytokines (TNF-α, IL-1β, and IL-6), glutamic-pyruvic transaminase(GPT), and glutamic-oxaloacetic transaminase (GOT) were reduced via SeY supplemented, and serum concentrations of immunoglobulins A (IgA), IgG, and activities of antioxidant enzymes such as the superoxide dismutase (SOD), catalase (CAT) ,and glutathione peroxidase (GSH-Px) were improved in the diquat-challenged pigs (P < 0.05). In addition, SeY supplementation acutely enhanced the activities of these antioxidant enzymes in the liver and thymus upon diquat challenge, which involved with the upregulation of the critical genes related antioxidant signaling such as the nuclear factor erythroid-derived 2-related factor 2 (Nrf-2) and heme oxygenase-1 (HO-1) (P < 0.05). Importantly, we also found that SeY supplementation apparently reduced the malondialdehyde (MDA) concentrations in the liver, thymus, and serum (P < 0.05). Specifically, the expression levels of TNF-α, IL-6, IL-1β, Toll-like receptor 4 (TLR-4), and nuclear factor-κB (NF-κB) in the liver and thymus were downregulated by SeY upon diquat challenge. These results suggested that SeY can attenuate oxidative stress-induced growth retardation, which was associated with elevating body antioxidant capacity, immune functions, and suppressed inflammatory response.

Fetal-Derived Immune Cells at the Roots of Lifelong Pathophysiology

Tissue-resident innate immune cells exert a wide range of functions in both adult homeostasis and pathology. Our understanding of when and how these cellular networks are established has dramatically changed with the recognition that many lineages originate at least in part from fetal sources and self-maintain independently from hematopoietic stem cells. Indeed, fetal-derived immune cells are found in most organs and serous cavities of our body, where they reside throughout the entire lifespan. At the same time, there is a growing appreciation that pathologies manifesting in adulthood may be caused by adverse early life events, a concept known as “developmental origins of health and disease” (DOHaD). Yet, whether fetal-derived immune cells are mechanistically involved in DOHaD remains elusive. In this review, we summarize our knowledge of fetal hematopoiesis and its contribution to adult immune compartments, which results in a “layered immune system.” Based on their ontogeny, we argue that fetal-derived immune cells are prime transmitters of long-term consequences of prenatal adversities. In addition to increasing disease susceptibility, these may also directly cause inflammatory, degenerative, and metabolic disorders. We explore this notion for cells generated from erythro-myeloid progenitors (EMP) produced in the extra-embryonic yolk sac. Focusing on macrophages and mast cells, we present emerging evidence implicating them in lifelong disease by either somatic mutations or developmental programming events resulting from maternal and early environmental perturbations.

Relationship between weaning age and antibiotic usage on pig growth performance and mortality

A total of 2,184 pigs (DNA 600 × PIC L42) were used to evaluate the effects of weaning age and antibiotic (AB) use on pig performance from weaning to marketing in a commercial production system. Experimental treatments were arranged in a 3 × 2 factorial with main effects of weaning age (18.5, 21.5, or 24.5 d of age) and with the use of ABs or an antibiotic-free (NAE) program. At birth, pigs were ear tagged, and the date of birth and sex recorded. Pigs were weaned from a 4,000-sow farm over four consecutive weeks. Four weaning batches (one per week) of 546 pigs were used. Each weaning batch had one-third of pigs of each weaning age. Pigs were placed in pens by weaning age and then randomly assigned to an AB or NAE program. There were 14 replicate pens per treatment and 26 pigs per pen (13 barrows and 13 gilts). Pigs allocated to the AB program were fed a diet containing 441 mg/kg chlortetracycline (CTC) from day 8 to 21 postweaning. They were also administered 22 mg/kg of body weight (BW) of CTC via drinking water for five consecutive days after a porcine respiratory and reproductive syndrome outbreak during week 7 after weaning. In the first 42 d postweaning, increasing weaning age improved (linear, P < 0.001) BW at day 42, average daily gain (ADG), and average daily feed intake (ADFI). From weaning to 197 d of age, increasing weaning age increased (linear, P < 0.001) ADG and ADFI. Pigs on the AB program had greater (P = 0.031) ADG and ADFI compared with NAE pigs. An interaction (linear, P = 0.005) was observed for feed efficiency (G:F). When ABs were provided, increasing weaning age did not result in any change in G:F; however, in the NAE program, increasing weaning age increased G:F. Pigs on the AB program had lower (P < 0.001) total losses (mortality and removals) than those on the NAE program. Increasing weaning age marginally (linear, P = 0.097) decreased total losses. Increasing weaning age decreased (quadratic, P < 0.001) the number of pigs treated with an injectable AB but the AB program did not (P = 0.238). The weight sold (at 197 d of age) per pig weaned was increased (linear, P = 0.050) by increasing weaning age and by using AB in feed and water (P = 0.019). In summary, increasing weaning age linearly improved most of the pig performance criteria and relatively the short-term use of ABs reduced mortality and removals with both factors contributing to increased weight sold per pig weaned.

Effects of Mast Cells Induced by NSAIDs Impair Intestinal Epithelial Barrier Function In Vivo and In Vitro

To explore the correlation between altered expression of mast cells and PAR-2 and impaired mucosal barrier in NSAIDs enteropathy through animal and cell experiments, and to elucidate the role of mast cells and PAR-2 in the pathogenesis of NSAIDs enteropathy and the regulatory mechanism of the tight junction of intestinal epithelium. Animal experiments: the NSAIDs-related small intestine injury model was established by intragastric administration of diclofenac sodium, and mast cells were detected by toluidine blue staining. Cell experiments: Intestinal epithelial cell line (IEC-6) was applied with diclofenac sodium and its activity was detected by CCK-8.IEC-6 and RBL-2H3 were co-cultured to evaluate the permeability of intestinal epithelial cells by detecting the concentration of potassium ion and LDH. The expressions of tight junction proteins (zo-1, claudin-1, occludin), cytoskeletal components (actin, tubulin, keratin) and par-2 were analyzed by Western Blot. In animal experiments, the number of mast cells was significantly increased after 24 h of action of diclofenac sodium. In cell experiments, the survival rate of IEC-6 cells decreased significantly when the concentration of diclofenac sodium is more than 50 μg/mL; after 24 h of co-culture, the potassium and LDH concentration in the co-culture group were significantly higher, and the expression of ZO-1, claudin-1, occludin, tubulin, and keratin was decreased. Mast cells activate PAR-2 in intestinal epithelial cells, downregulate the related proteins of cell tight junctions and cytoskeletal proteins, and increase the permeability of intestinal epithelial cells.

Maintaining continuity of nutrient intake after weaning. I. Review of pre-weaning strategies

Weaning is a crucial phase of swine production marked by a multitude of biological and environmental stressors, which have a significant impact on immediate postweaning behavior and feed intake (FI). During this time, the piglet's gastrointestinal (GI) system is also undergoing extensive epithelial, immune, and nervous system development. In this review, our objective is to describe the different preweaning strategies that can be used to minimize nutrient intake disruption and improve FI in the immediate postweaning period. Reducing nutrient disruption postweaning can be accomplished through the implementation of management and nutritional strategies. Research consistently demonstrates that weaning older, more developmentally mature pigs helps prevent many of the adverse GI effects associated with weaning stress. Providing creep feed to pigs during lactation is another reliable strategy that has been shown to increase immediate postweaning FI by acclimating pigs to solid feed prior to weaning. Likewise, socialization by allowing pigs to mix before weaning improves social skills, minimizing mixing stress, and aggression-related injury immediately postweaning. Supplemental milk replacer has also been shown to elicit a positive response in preweaning growth performance, which may help to reduce preweaning mortality. While socialization and milk replacer are acknowledged to ease the weaning transition, these strategies have not been widely adopted due to labor and application challenges. Additionally, the cost of milk replacer and logistics of retrofitting farrowing houses to accommodate litter socialization have limited adaptation. Further exploration of maternal nutrition strategies, particularly fetal imprinting, is needed to better understand the implications of perinatal learning. Other areas for future research include, combining environmental enrichment with feeding strategies, such as large destructible pellets or play feeders, as well as determining at what time point producers should start socializing pigs before weaning. While more research is needed to develop strategic preweaning management programs, many of the strategies presented in this review provide opportunities for producers to minimize nutrient intake disruption by preventing feed neophobia, reducing stress, and easing the wean pig transition.

Quercetin Alleviates Oxidative Damage by Activating Nuclear Factor Erythroid 2-Related Factor 2 Signaling in Porcine Enterocytes

Oxidative stress has been implicated in the etiology of multiple gastrointestinal disorders, such as irritable bowel syndrome and inflammatory bowel disease. This study was conducted to evaluate effects of natural product quercetin on diquat-induced oxidative stress in porcine enterocytes and underlying mechanisms. Intestinal porcine epithelial cell line 1 (IPEC-1) cells pretreated with or without quercetin (5 μM, 24 h) were incubated with vehicle or diquat (100 μM) for 6 h. The results showed that diquat treatment induced apoptosis in a caspase-3-dependent manner, as accompanied by elevated reactive oxygen species (ROS) production, increased mitochondrial depolarization, and reduced the abundance of tight junction proteins. These adverse effects of diquat were remarkably abrogated by quercetin administration. Further study indicated that the protective effect of quercetin was associated with elevated protein abundance of nuclear factor erythroid 2-related factor 2 (Nrf2) and increased intracellular glutathione (GSH) content. Interestingly, the beneficial effects of quercetin on diquat-induced oxidative damage were abolished by all-trans-retinoic acid (Atra), a specific inhibitor of Nrf2, indicating a Nrf2-dependent regulation manner. The results show that quercetin attenuates diquat-induced cell injury by promoting protein abundance of Nrf2 and regulating GSH-related redox homeostasis in enterocytes. These findings provide new insights into a function role of quercetin in maintaining intestinal homeostasis.

Histamine-dependent interactions between mast cells, glia, and neurons are altered following early-life adversity in mice and humans

Early-life adversity contributes to the development of functional bowel disorders later in life through unresolved mechanisms. Here, we tested the hypothesis that early-life adversity alters anatomical and functional interactions between mast cells and enteric glia. The effects of early-life stress were studied using the neonatal maternal separation (NMS) stress mouse model. Anatomical relationships between mast cells and enteric glia were assessed using immunohistochemistry and mast cell reporter mice (Mcpt5^Cre;GCaMP5g-tdT). Immunohistochemistry was used to assess the expression of histamine, histamine 1 (H1) receptors, and glial fibrillary acidic protein. Functional responses of glia to mast cell mediators were assessed in calcium imaging experiments using Sox10^CreERT2;GCaMP5g-tdT mice and cultured human enteric glial cells. NMS increases mast cell numbers at the level of the myenteric plexus and their proximity to myenteric ganglia. Myenteric glia respond to mediators released by activated mast cells that are blocked by H1 receptor antagonists in mice and humans and by blocking neuronal activity with tetrodotoxin in mouse tissue. Histamine replicates the effects of mast cell supernatants on enteric glia, and NMS increases histamine production by mast cells. NMS reduces glial responses to mast cell mediators in mouse tissue, while potentiating responses in cultured human enteric glia. NMS increases myenteric glial fibrillary acidic protein expression and reduces glial process length but does not cause neurodegeneration. Histamine receptor expression is not altered by NMS and is localized to neurons in mice, but glia in humans. Early-life stress increases the potential for interactions between enteric glia and mast cells, and histamine is a potential mediator of mast cell-glial interactions through H1 receptors. We propose that glial-mast cell signaling is a mechanism that contributes to enteric neuroplasticity driven by early-life adversity.NEW & NOTEWORTHY Early-life adversity places an individual at risk for developing functional gastrointestinal disorders later in life through unknown mechanisms. Here, we show that interactions between mast cells and glia are disrupted by early-life stress in mice and that histamine is a potential mediator of mast cell-glial interactions.

Environmental stressors affect intestinal permeability and repair responses in a pig intestinal ischemia model

The pig is a powerful model for intestinal barrier studies, and it is important to carefully plan animal care and handling for optimal study design as psychological and physiological stressors significantly impact intestinal mucosal barrier function. Here, we report the effects of a period of environmental acclimation versus acute transport stress on mucosal barrier repair after intestinal ischemic injury. Jejunal ischemia was induced in young pigs which had been allowed to acclimate to a biomedical research housing environment or had been transported immediately prior to experimental injury (non-acclimated). Mucosa was then incubated ex vivo on Ussing chambers. In uninjured mucosa, there was no difference in transepithelial electrical resistance (TEER) or epithelial integrity between groups. However, acclimated pigs had increased macromolecular flux as compared to non-acclimated pigs during the first hour of ex vivo incubation. Ischemia induced greater epithelial loss in non-acclimated pigs as compared to acclimated pigs, yet this group achieved greater wound healing during recovery. Non-acclimated pigs had more robust TEER recovery ex vivo following injury versus acclimated pigs. The expression pattern of the tight junction protein claudin-4 was disrupted in acclimated pigs following recovery but showed enhanced localization to the apical membrane in non-acclimated pigs following recovery. Acute transport stress increases mucosal susceptibility to epithelial loss but also primes the tissue for a more robust barrier repair response. Alternatively, environmental acclimation increases leak pathway and diminishes barrier repair responses after ischemic injury.

Glucagon-like peptide 2 attenuates intestinal mucosal barrier injury through the MLCK/pMLC signaling pathway in a piglet model

Glucagon-like peptide-2 (GLP-2), an intestinotrophic hormone, has drawn considerable attention worldwide due to its potential to promote intestinal development. We investigated the effects and mechanisms of GLP-2 against lipopolysaccharide (LPS)-induced intestinal inflammation and injury both in vitro and in vivo. Forty healthy piglets weaned at the age of 28 days with similar body weight (BW) were assigned to four in vivo treatments with ten piglets each: (i) nonchallenged control; (ii) LPS-challenged control; (iii) LPS + low dose GLP-2; and (iv) LPS + high dose GLP-2. Piglets were subcutaneously injected with phosphate-buffered saline supplemented with GLP-2 at doses of 0, 0, 2, and 10 nmol/kg BW per day for seven consecutive days. The piglets were challenged with an intraperitoneal injection with 100 μg/kg LPS on day 14 to induce intestinal damage. After that, the gene and protein expression levels of representative tight junction proteins and myosin light-chain kinase (MLCK)/phosphorylated myosin light chain (pMLC), as well as proinflammatory cytokine levels were determined using quantitative reverse transcription polymerase chain reaction, western blot, and enzyme-linked immunosorbent assay methods. A high dose of GLP-2 pretreatment increased intestinal permeability by downregulating and redistributing tight junction proteins (p < .05), for example, zona occluden-1 (ZO-1) and occludin. GLP-2 decreased the transcription of proinflammatory cytokines genes including interleukin-1β (IL-1β), IL-6, IL-8, and tumor necrosis factor-α in small intestines (p < .05). GLP-2 prevented the LPS-induced increase in the expression of MLCK dose-dependently and the increase in pMLC levels in the duodenum, jejunum, and ileum. To assess further the protective effect of GLP-2 on LPS-induced intestinal barrier injury after weaning and its possible mechanism, an in vitro intestinal epithelial barrier model was established with IPEC-J2 monolayers and treated with 100 μg/ml LPS with or without 1 × 10^-8  mol/L GLP-2 pretreatment. The in vitro analysis included control, LPS, and GLP-2 + LPS treatments. GLP-2 treatment alleviated the destructive effect of LPS on barrier permeability by restoring the expression and ultrastructure of ZO-1 and occludin (p < .05). In addition, GLP-2 reversed the LPS-induced MLCK hyperexpression and pMLC hyperphosphorylation (p < .05). Taken together, our findings revealed a mechanism by which GLP-2 alleviated LPS-challenged intestinal barrier injury and inflammation in weaned piglets and IPEC-J2 cells via the MLCK/pMLC signaling pathway.

Underlying mechanisms for intestinal diseases arising from stress

Stress is an instinctive defense mechanism of the body in the competition for survival, but long-term or chronic stress will lead to systemic pathological manifestations. Intestinal diseases are closely related to pathological stress. This paper reviews the pathogenesis of intestinal diseases arising from stress.

Early weaning alters redox status in the hippocampus and hypothalamus of rat pups

Exposure to environmental factors can program the metabolism, conferring resistance or increasing the risk to chronic disease development in childhood and adulthood. In this sense, lactation is an important period in this window of development. Herein, we investigated the effect of early weaning on neurochemical and behavioral changes in offspring at weaning and adulthood. Female and male pups were divided into four groups: (1) Control weaning (weaning on the PND21, pups were kept with the biological mother); (2) Early Weaning Bromocriptine group (EWB) (pharmacological weaning on PND16); (3) Early Weaning Cross-Fostering group (EWCF) (pups housed with a foster mother on PND16 up to PND21); (4) Early Weaning Without Care group (EWWC) (weaning on PND16, maternal separation). Weight control of pups was recorded from postnatal Day 16 to 59. On the 21st day, part of the pups was euthanized and the hippocampus and hypothalamus were removed for biochemical evaluation. The remaining pups were submitted to behavioral tests on the 60th postnatal day. Early weaning reduced the pups' body weight, in a sex-dependent way. At 60 days of age, male pups of EWCF and EWWC groups have lower body weight compared to control male, and female body weight was lower than male pups. In relation to biochemical changes in the brain, weaning altered the levels of oxidants, increased the enzymatic activity of superoxide dismutase (SOD), and glutathione peroxidase (GPx), as well as induced lipid peroxidation. Weaning was also able to alter long-term memory and induce anxious behavior in pups. Our results demonstrate that the different types of early weaning changed the parameters of redox status in the hippocampus and hypothalamus of pups (21 days old), suggesting a prooxidative profile, in addition, to alter learning/memory and inducing an anxious behavior in male offspring (60 days old).

Effects of GABA Supplementation on Intestinal SIgA Secretion and Gut Microbiota in the Healthy and ETEC-Infected Weanling Piglets

Pathogenic enterotoxigenic Escherichia coli (ETEC) has been considered a major cause of diarrhea which is a serious public health problem in humans and animals. This study was aimed at examining the effect of γ-aminobutyric acid (GABA) supplementation on intestinal secretory immunoglobulin A (SIgA) secretion and gut microbiota profile in healthy and ETEC-infected weaning piglets. A total of thirty-seven weaning piglets were randomly distributed into two groups fed with the basal diet or supplemented with 40 mg·kg-1 of GABA for three weeks, and some piglets were infected with ETEC at the last week. According to whether ETEC was inoculated or not, the experiment was divided into two stages (referred as CON1 and CON2 and GABA1 and GABA2). The growth performance, organ indices, amino acid levels, and biochemical parameters of serum, intestinal SIgA concentration, gut microbiota composition, and intestinal metabolites were analyzed at the end of each stage. We found that, in both the normal and ETEC-infected piglets, jejunal SIgA secretion and expression of some cytokines, such as IL-4, IL-13, and IL-17, were increased by GABA supplementation. Meanwhile, we observed that some low-abundance microbes, like Enterococcus and Bacteroidetes, were markedly increased in GABA-supplemented groups. KEGG enrichment analysis revealed that the nitrogen metabolism, sphingolipid signaling pathway, sphingolipid metabolism, and microbial metabolism in diverse environments were enriched in the GABA1 group. Further analysis revealed that alterations in microbial metabolism were closely correlated to changes in the abundances of Enterococcus and Bacteroidetes. In conclusion, GABA supplementation can enhance intestinal mucosal immunity by promoting jejunal SIgA secretion, which might be related with the T-cell-dependent pathway and altered gut microbiota structure and metabolism.

Deep-Fried Atractylodis Rhizoma Protects against Spleen Deficiency-Induced Diarrhea through Regulating Intestinal Inflammatory Response and Gut Microbiota

According to the theories of traditional Chinese medicine, spleen deficiency often leads to diarrhea, and deep-fried Atractylodis Rhizoma (DAR) is commonly used for the treatment. However, the association between spleen deficiency and diarrhea remains unclear. The present study aimed to investigate the therapeutic effect of DAR for the treatment of diarrhea caused by spleen deficiency and analyze the related mechanisms. It was found that a high dose group of an ethanolic extract of deep-fried Atractylodis Rhizoma (EEDAR-H) significantly inhibited weight loss, diarrhea, and pathological changes in colon tissue induced by rhubarb. EEDAR-H was found to significantly reduce the level of intestinal inflammatory cytokines and increase the expression of gastrointestinal motility hormones. In addition, EEDAR-H significantly increased the expression of aquaporin 3 (AQP3) and aquaporin 8 (AQP8) and restored abnormal water metabolism; Shen-Ling-Bai-Zhu-San (SLBZS) induced the same effect as EEDAR-H. Additional tests on the mechanism found that EEDAR-H and SLBZS promoted the integrity of the intestinal barrier. Both significantly increased the expression of the tight junction protein ZO-1 and Occludin, inhibited the phosphorylation of p38MAPK and MLC, and significantly reduced the expression levels of PAR-2. Analysis of the gut microbiota indicated that overall changes in its structure were reversed after treatment with EEDAR-H or SLBZS, in addition to significant modulation of the abundance of different phyla. At the genus level, EEDAR-H or SLBZS significantly reduced the levels of potential pathogens and increased those of beneficial bacteria.

Review: innovation through research in the North American pork industry

This article involved a broad search of applied sciences for milestone technologies we deem to be the most significant innovations applied by the North American pork industry, during the past 10 to 12 years. Several innovations shifted the trajectory of improvement or resolved significant production limitations. Each is being integrated into practice, with the exception being gene editing technology, which is undergoing the federal approval process. Advances in molecular genomics have been applied to gene editing for control of porcine reproductive and respiratory syndrome and to identify piglet genome contributions from each parent. Post-cervical artificial insemination technology is not novel, but this technology is now used extensively to accelerate the rate of genetic progress. A milestone was achieved with the discovery that dietary essential fatty acids, during lactation, were limiting reproduction. Their provision resulted in a dose-related response for pregnancy, pregnancy maintenance and litter size, especially in maturing sows and ultimately resolved seasonal infertility. The benefit of segregated early weaning (12 to 14 days of age) was realized for specific pathogen removal for genetic nucleus and multiplication. Application was premature for commercial practice, as piglet mortality and morbidity increased. Early weaning impairs intestinal barrier and mucosal innate immune development, which coincides with diminished resilience to pathogens and viability later in life. Two important milestones were achieved to improve precision nutrition for growing pigs. The first involved the updated publication of the National Research Council nutrient requirements for pigs, a collaboration between scientists from America and Canada. Precision nutrition advanced further when ingredient description, for metabolically available amino acids and net energy (by source plant), became a private sector nutrition product. The past decade also led to fortuitous discoveries of health-improving components in ingredients (xylanase, soybeans). Finally, two technologies converged to facilitate timely detection of multiple pathogens in a population: oral fluids sampling and polymerase chain reaction (PCR) for pathogen analysis. Most critical diseases in North America are now routinely monitored by oral fluid sampling and prepared for analysis using PCR methods.

Endocrine Disruption and Reproductive Pathology

During the past 20 years, investigations involving endocrine active substances (EAS) and reproductive toxicity have dominated the landscape of ecotoxicological research. This has occurred in concert with heightened awareness in the scientific community, general public, and governmental entities of the potential consequences of chemical perturbation in humans and wildlife. The exponential growth of experimentation in this field is fueled by our expanding knowledge into the complex nature of endocrine systems and the intricacy of their interactions with xenobiotic agents. Complicating factors include the ever-increasing number of novel receptors and alternate mechanistic pathways that have come to light, effects of chemical mixtures in the environment versus those of single EAS laboratory exposures, the challenge of differentiating endocrine disruption from direct cytotoxicity, and the potential for transgenerational effects. Although initially concerned with EAS effects chiefly in the thyroid glands and reproductive organs, it is now recognized that anthropomorphic substances may also adversely affect the nervous and immune systems via hormonal mechanisms and play substantial roles in metabolic diseases, such as type 2 diabetes and obesity.

Nutritional Regulation of Gut Barrier Integrity in Weaning Piglets

Simple Summary

Weaning is a very stressful period in the piglet’s life in intensive farming: it is a sudden process occurring between three to four weeks of age, when the gastrointestinal tract (GIT) is still immature. The GIT is formed by the epithelial, immune and enteric nervous system which controls epithelial barrier integrity as well as gut functions including the transport of luminal nutrients, water and electrolytes. Early weaning is characterized by a breakdown of these gut functions, an increase in intestinal permeability and the appearance of gastrointestinal functional disorders, which can have long-lasting consequences in the pig’s life. Weaning, therefore, requires the correct level of nutrients, high quality ingredients, and management, which are directed primarily at encouraging rapid feed intake whilst reducing mortality and morbidity. This review describes the organization of the GIT and highlights the interactions between feed components and the morphology and physiology of the epithelial barrier. Novel dietary strategies focused on improving gut health are also discussed, considering the impacts of selected feed ingredients or additives on the GIT such as functional amino acids, phytochemicals and organic acids.

Abstract

Weaning is very stressful for piglets and leads to alterations in the intestinal barrier, a reduction in nutrient absorption and a higher susceptibility to intestinal diseases with heavy economic losses. This review describes the structures involved in the intestinal barrier: the epithelial barrier, immune barrier and the enteric nervous system. Here, new insights into the interactions between feed components and the physiology and morphology of the epithelial barrier are highlighted. Dietary strategies focused on improving gut health are also described including amino acids, phytochemicals and organic acids.

Effect of fermented blood cells on growth performance and intestinal characteristics of weaned piglets

The increase in feed costs has led feeder to replace protein source. Blood meal can be used in piglet diets instead of fish meal (FM). The objective of this study was to investigate the effect of fermented blood cells (FBCs) on the growth performance and intestinal health of weaned piglets. One hundred eighty 28-day-old piglets were assigned and were divided into 4 groups (9 L per groups and 5 pigs per litters) randomly. The piglets were fed one of four experimental diets, fish meal, blood cells (BCs), liquid-state fermented blood cells (LFBCs) or solid-state fermented blood cells (SFBCs) respectively. The dietary with LFBCs and SFBCs increased the average daily gain and feed intake (ADFI) and average daily gain (ADG) (p < .05). In duodenum, LFBC group increased the villous height (p < .05). The SFBC and LFBC group significantly increased the villous height (p < .05) in the jejunum. Fermented blood cells exhibit a positive regulatory function on the intestinal tract and modulate intestinal microflora. Compared with the fish meal group, the CAT, GSH-PX and SOD activity, and MDA level was no significant differences in jejunum and plasma of weaned piglets (p > .05). LFBCs and SFBCs significantly increased the bifidobacteria and lactobacillus number in the caecum (p < .05). Dietary LFBCs increased the expression of ZO-1 mRNA in the jejunal of weaned piglets (p < .05). In conclusion, dietary with fermented blood cells in weaned piglets had improved growth performance and intestinal health of weaned piglets.

Rapid Communication: The relationship of enterocyte proliferation with intestinal morphology and nutrient digestibility in weaning piglets

Understanding the regulatory mechanisms of intestinal morphology and function is essential for improving postweaning growth in pigs. The objective of this study was to identify the relationships of enterocyte proliferation with intestinal villus height, crypt depth, and nutrient digestibility in piglets. Sixty-four 21-d-old weaned piglets were used. Gastrointestinal cell proliferation was evaluated via Ki-67 immunohistochemistry. Villus height and crypt depth were measured using hematoxylin and eosin (H&E)-stained sections. The apparent total tract digestibility (ATTD) of CP and GE was determined by chemical analysis. The activities of lactase and sucrase were determined with commercial kits. Western blot was carried out to assess the expression of nutrient transporters. The number of Ki-67 positive cells was associated with villus height (r = 0.548, P < 0.001) and crypt depth (r = 0.759, P < 0.001) in the jejunum. The number of Ki-67 positive cells was also associated with the ATTD of CP (r = 0.715, P = 0.001). Furthermore, a positive relationship between Ki-67 positive cell populations and lactase activity (r = 0.559, P < 0.001) was observed. Additionally, the number of Ki-67 positive cells was associated with the protein expression levels of nutrient transporters PEPT1 (r = 0.511, P = 0.030) and SGLT1 (r = 0.601, P = 0.014). Weak relationships were found between Ki-67 positive cell numbers and the ATTD of GE (r = 0.401, P = 0.099) and the activity of sucrase (r = 0.313, P = 0.087). In conclusion, enterocyte proliferation was positively associated with intestinal villus height, crypt depth, and nutrient digestibility in weaning piglets. Our findings suggested that intestinal morphology and function can be improved by regulating epithelial cell proliferation in piglets.

Nimbolide protects against endotoxin-induced acute respiratory distress syndrome by inhibiting TNF-α mediated NF-κB and HDAC-3 nuclear translocation

Acute respiratory distress syndrome (ARDS) is characterized by an excessive acute inflammatory response in lung parenchyma, which ultimately leads to refractory hypoxemia. One of the earliest abnormalities seen in lung injury is the elevated levels of inflammatory cytokines, among them, the soluble tumor necrosis factor (TNF-α) has a key role, which exerts cytotoxicity in epithelial and endothelial cells thus exacerbates edema. The bacterial lipopolysaccharide (LPS) was used both in vitro (RAW 264.7, THP-1, MLE-12, A549, and BEAS-2B) and in vivo (C57BL/6 mice), as it activates a plethora of overlapping inflammatory signaling pathways involved in ARDS. Nimbolide is a chemical constituent of Azadirachta indica, which contains multiple biological properties, while its role in ARDS is elusive. Herein, we have investigated the protective effects of nimbolide in abrogating the complications associated with ARDS. We showed that nimbolide markedly suppressed the nitrosative-oxidative stress, inflammatory cytokines, and chemokines expression by suppressing iNOS, myeloperoxidase, and nitrotyrosine expression. Moreover, nimbolide mitigated the migration of neutrophils and mast cells whilst normalizing the LPS-induced hypothermia. Also, nimbolide modulated the expression of epigenetic regulators with multiple HDAC inhibitory activity by suppressing the nuclear translocation of NF-κB and HDAC-3. We extended our studies using molecular docking studies, which demonstrated a strong interaction between nimbolide and TNF-α. Additionally, we showed that treatment with nimbolide increased GSH, Nrf-2, SOD-1, and HO-1 protein expression; concomitantly abrogated the LPS-triggered TNF-α, p38 MAPK, mTOR, and GSK-3β protein expression. Collectively, these results indicate that TNF-α-regulated NF-κB and HDAC-3 crosstalk was ameliorated by nimbolide with promising anti-nitrosative, antioxidant, and anti-inflammatory properties in LPS-induced ARDS.

Associations between gastrointestinal-tract function and the stress response after weaning in pigs

Psychosocial stress is a major factor driving gastrointestinal-tract (GIT) pathophysiology and disease susceptibility in both humans and animals. Young weaned pigs typically undergo psychosocial and environmental stressors associated with production practices, including separation from their dam, mixing and crowding stress, transport and changed temperature and air-quality parameters, all of which can have significant deleterious impacts not only on performance but also on GIT structure and function, and, therefore, pig health and welfare. Strategies addressing some of these issues are explored in the current review, as well as discussion pertaining to sexual dimorphism in young pigs linked to stressful experiences, with young female pigs seemingly adversely affected more than their male counterparts. However, mechanisms governing susceptibility to stress-induced GIT functionality and disease remain inadequately understood.

Effects of Quercetin on Proliferation and H₂O₂-Induced Apoptosis of Intestinal Porcine Enterocyte Cells

Weanling stress and toxicosis, which are harmful to the health of pigs' intestines, are associated with oxidative stress. Quercetin (Que) is a polyphenolic compound that shows good anti-cancer, anti-inflammation and anti-oxidation effects. This study aimed to elaborate whether or not Que promotes IPEC-J2 (intestinal porcine enterocyte cells) proliferation and protects IPEC-J2 from oxidative damage. Thus, we examined the effects of Que on proliferation and H₂O₂-induced apoptosis in IPEC-J2. The results showed that Que increased IPEC-J2 viabililty, propelled cells from G1 phase into S phase and down-regulated gene levels of P27 and P21, respectively. Besides, H₂O₂-induced cell damage was alleviated by Que after different exposure times, and Que depressed apoptosis rate, reactive oxygen species (ROS) level and percentage of G1 phase cells and elevated the percentage of cells in G2 phase and S phase and mitochondrial membrane potential (Δψm) after IPEC-J2 exposure to H₂O₂. Meanwhile, Que reduced the value of Bax/Bcl-2 in H₂O₂ exposed cells. In low-degree oxidative damage cells, lipid peroxidation product malondialdehyde (MDA) content and superoxide dismutase (SOD) activity were increased. In turn, Que could reverse the change of MDA content and SOD activity in low-degree damage cells. Nevertheless, catalase (CAT) activity was not changed in IPEC-J2 incubated with Que under low-degree damage conditions. Interestingly, relative expressive levels of the proteins claudin-1 and occludin were not altered under low-degree damage conditions, but Que could improve claudin-1 and occludin levels, slightly. This research indicates that Que can be greatly beneficial for intestinal porcine enterocyte cell proliferation and it protects intestinal porcine enterocyte cells from oxidation-induced apoptosis, and could be used as a potential feed additive for porcine intestinal health against pathogenic factor-induced oxidative damages and apoptosis.

Gastrointestinal tract (gut) health in the young pig

An optimally functioning gastrointestinal tract (GIT) clearly is of importance to the overall metabolism, physiology, disease status and performance of pigs of all stages of growth and development. Recently, the 'health' of the GIT ('gut health') has attracted much attention despite the lack of a clear definition to the term or its aetiology, although in broad terms, 'gut health' encompasses a number of physiological and functional features including nutrient digestion and absorption, host metabolism and energy generation, a stable and appropriate microbiota/microbiome, defence mechanisms including barrier function and mucosal immune mechanisms, and the interactions between these components. 'Gut health' in the newly-weaned (young) pig is of obvious interest due to changes in GIT structure and function associated with the post-weaning transition, and more recently to the upsurge in interest in different feed additives as dietary alternatives/replacements caused by bans/reductions in certain antimicrobial compounds being available in some parts of the world. In the presence of enteric disease(s) after weaning, a deterioration in 'gut health' may be synonymous to the overall health of the pig, and although some direct relationships can be drawn between pig performance and efficiency and a 'healthy' GIT, sometimes this connection is subtler and less obvious, especially in the absence of overt enteric disease(s). The factors and conditions involved in 'gut health' are multifactorial, complex, often poorly described and sometimes incorrectly interpreted, although it is evident that perturbations of the GIT can cause an imbalance and disturb the generalized homeostasis. In addition to any enteric diseases or conditions that might arise as a result of these disturbances, other influences will also impact such as the responses occurring in the GIT in the period immediately after weaning, any changes that might occur after a change in diet, and (or) disruptions to meal patterns and hence the flow of nutrients. Ultimately, 'gut health' represents the outcome of the GIT in response to its capacity and ability to respond and adapt to the insults and challenges it encounters.

The stress concept in gastroenterology: from Selye to today

More than eighty years after Hans Selye (1907-1982) first developed a concept describing how different types of environmental stressors affect physiological functions and promote disease development (called the "general adaptation syndrome") in 1936, we herein review advances in theoretical, mechanistic, and clinical knowledge in stress research, especially in the area of gastroenterology, and summarize progress and future perspectives arising from an interdisciplinary psychoneurobiological framework in which genetics, epigenetics, and other advanced ( omics) technologies in the last decade continue to refine knowledge about how stress affects the brain-gut axis in health and gastrointestinal disease. We demonstrate that neurobiological stress research continues to be a driving force for scientific progress in gastroenterology and related clinical areas, inspiring translational research from animal models to clinical applications, while highlighting some areas that remain incompletely understood, such as the roles of sex/gender and gut microbiota in health and disease. Future directions of research should include not only the genetics of the stress response and resilience but also epigenetic contributions.

Role of serotonin in the intestinal mucosal epithelium barrier in weaning mice undergoing stress-induced diarrhea

Stress-induced diarrhea is a frequent and challenging threat to humans and domestic animals. Serotonin (5-HT) has been shown to be involved in the pathological process of stress-induced diarrhea. However, the role of 5-HT in stress-induced diarrhea remains unclear. A stress-induced diarrhea model was established in 21-day-old ICR weaning mice through an intragastric administration of 0.25 mL of 0.4 g/mL folium sennae and restraint of the hind legs with adhesive tape for 4 h to determine whether 5-HT regulates the mucosal barrier to cause diarrhea. Mice with decreased levels of 5-HT were pretreated with an intraperitoneal injection of 300 mg/kg p-chlorophenylalanine (PCPA), a 5-HT synthesis inhibitor. After 5 days of treatment, the stress level, body weight and intestinal mucosal morphology indexes were measured. Compared to the controls, the mice with stress-induced diarrhea displayed a stress reaction, with increased corticosterone levels, as well as increased 5-HT-positive cells. However, the mice with stress-induced diarrhea exhibited decreased body weights, villus height to crypt depth ratios (V/C), and Occludin and Claudin1 expression. The PCPA injection reversed these effects in mice with different degrees of stress-induced diarrhea. Based on these findings, inhibition of 5-HT synthesis relieved the stress response and improved the health of the intestinal tract, including both the intestinal absorption capacity, as determined by the villus height and crypt depth, and the mucosal barrier function, as determined by the tight junction proteins of epithelial cell.

Weaning stress and gastrointestinal barrier development: Implications for lifelong gut health in pigs

The gastrointestinal (GI) barrier serves a critical role in survival and overall health of animals and humans. Several layers of barrier defense mechanisms are provided by the epithelial, immune and enteric nervous systems. Together they act in concert to control normal gut functions (e.g., digestion, absorption, secretion, immunity, etc.) whereas at the same time provide a barrier from the hostile conditions in the luminal environment. Breakdown of these critical GI functions is a central pathophysiological mechanism in the most serious GI disorders in pigs. This review will focus on the development and functional properties of the GI barrier in pigs and how common early life production stressors, such as weaning, can alter immediate and long-term barrier function and disease susceptibility. Specific stress-related pathophysiological mechanisms responsible for driving GI barrier dysfunction induced by weaning and the implications to animal health and performance will be discussed.

Impaired intestinal barrier function and relapsing digestive disease: Lessons from a porcine model of early life stress

Within this issue of Neurogastroenterology and Motility, an article by Pohl et al highlights new insights from a powerful porcine model of the link between early life adversity and relapsing functional gastrointestinal disorders. Early weaning stress closely mimics the early life psychosocial stressors that have been linked to adult onset gastrointestinal dysfunction. This early weaning model provides reproducible and highly translatable outcomes in young stress-challenged pigs. Due to the convincingly comparable neurological and gastroenterological anatomy and physiology between pigs and human beings, gastrointestinal stress and injury studies utilizing swine models will provide invaluable insights to improve our understanding and treatment of gastrointestinal disease in human beings. Future studies to examine mechanisms underlying this link between early life adversity and functional gastrointestinal disorders will explore the roles of gender and hypomaturity in gastrointestinal responses to stress.